Electrical connector with contactprotecting and arc-quenching shield



Aug. 29, 1967 DALY 3,339,039

D. F. ELECTRICAL CONNECTOR WITH CONTACT-PROTECTING AND ARC-QUENCHINGSHIELD Filed Sept. 10, 1965 F/G/ F/GZ I'@ /0 1 W I" I N 60 6.2 (i 1/ f,I m,

IVENTOR.

00/7/29/ FDa/y BY h/s af/omeys United States Patent 3,339,039 ELECTRICALCONNECTOR WITH CONTACT- PROTECTING AND ARC-QUENCHING SHIELD Daniel F.Daly, Newington, Conn., assignor to The Arrow-Hart & Hegeman ElectricCompany, Hartford, Conn., a corporation of Connecticut Filed Sept. 10,1965, Ser. No. 486,300 2 Claims. (Cl. ZOO-51.09)

This invention relates to connectors and, more particularly, to heavyduty electrical connectors for carrying current up to about 60 amperesup to about 250 volts DC. or about 600 volts A.C.

Connectors of the sort to which this invention relates as heretoforemade failed the Underwriters tests requiring safe interruption ofoverloads a given number of times. For example, a connector to bear a 60a., 600 V. DC. or 250 v. A.C. rating should be able to withstandinterruptions satisfactorily of a 90 ampere current. Often the arcsdrawn between the contacts would jump to the metallic protective shellwhich was grounded, or the contacts burned away before the test wascompleted.

Therefore, one object of the invention is to provide an improvedconnector structure having superior arc quenching ability whilepreserving all the desirable attributes of prior heavy duty connectors.

Another object is to provide an improved wire terminal and groundingcontact for such heavy duty electrical connectors.

Other objects and advantages will appear as the invention is describedin connection with the accompanying drawing.

In the drawing:

FIG. 1 is a side elevation view, partly broken away and partly insection, of a plug and receptacle embodying the invention.

FIG. 2 is a view of the plug and receptacle parts of FIG. 1, partlybroken away and partly in section, with the plug partly inserted in thereceptacle.

FIG. 3 is a fragmentary perspective view of the faces of the receptacleand the plug.

FIG. 4 is a perspective view of the ground contact and terminal assemblyused in the combination of the previous figures.

Referring to the drawing, the connecting device embodying the inventioncomprises a receptacle part and a plug part which has shoe contactsadapted to be engaged with contacts in the receptacle.

The receptacle and plug are each encased in a metal cylindricalprotective shell 10, open at one end and having an aperture at theopposite end for passage of an electric cable.

Each shell has a molded insulating liner in its inner end.

The receptacle is formed of a base 12 of insulating material to which issecured by rivets or other common means, a housing portion which also isof insulating material. The base 12 has a circular disc-like portion 14on one side of which are mounted four identical equally spaced stampedsheet metal contacts such as 16, 17, 18 of L-shape. The longer or legportions of these contacts are transversely arcuate while their feet aresecured by rivets to the disc portion 14.

' From the opposite side of the disc, a post extends which issymmetrically longitudinally recessed to receive four identicalconventional equally spaced heavy wire terminals such as 20, 21 capableof handling conductors for 60 ampere current. The post is also recessedlongitudinally to receive a ground treminal and contact, designatedgenerally by numeral 70, as hereinafter described.

Mounted on and secured by rivets, bolts or otherwise to the base 12 is acylindrical hollow molded insulation housing portion 30 whose outsidediameter is the same as that of the disc portion 14. The housing 30surrounds and covers the receptacle contacts 16, 17, 18 and has recessesin its inner walls receiving said receptacle contacts.

The housing 30 has an opening in its end, above the tops of thereceptacle contacts 16-18, in which is slidably mounted a closure member40 in the form of a molded insulation disc having an irregularperipheral contour to fit into the complementary interior contour of thehousing opening. The closure slides upon a pin 41 centrally positionedand fixedly mounted on the disc portion 14. Urging the closureconstantly in position to close the opening in the housing and so as tocover and protect the receptacle contacts 16-18 is a coiled compressionspring 43 impaled on the pin 41. One end of the spring rests on the discportion 14 while the other presses against the inner surface of theclosure.

The closure is stopped in its outward movement, under urge of the spring43, by radial guides (not shown) abutting the outer ends of guidechannels (not shown) formed in the inner surface of the housing part 30.

The plug member comprises an insulating body 50 having a disc-likecentral portion 51 and axial posts 54, 56 extending therefrom onopposite sides.

The inner post 54 has four symmetrically placed longitudinal recessesreceiving four conventional wire terminals such as 6062. The post alsohas a fifth longitudinal recess to receive a fifth wire terminal andgrounding contact (not visible), as hereinafter described, for 5- wireusage.

The outer post 56 of the insulating body is cylindrical and has fourcontact shoes such as 66, 67, 68 mounted on lugs molded on thecylindrical surface at equally spaced positions and extending radiallybeyond the surface of the post. These contact shoes are each connectedto one of the wire terminals by connections within the post and notvisible. The outer face of each contact shoe is peripherally curved forrotatlve engagement with the respective receptacle contacts 16-18. Threeof the shoes such as 66, 67 are of equal size; the fourth 68 is largerand positioned nearer the end of the post than the other three. (Thefourth contact may be a ground contact in 4-wire usage.) Its differentshape provides for polarity identity.

Since the contact shoes extend beyond the periphery of the plug post 56,grooves 35, 36, 37 are provided in the periphery of the opening in thereceptacle housing part 30 for shoes 65', 66, 67 and a larger groove 38for the larger or grounding contact shoe 68.

When the plug post 56 is placed against the closure 40 and pushed, theclosure will be depressed permitting the post to enter the receptacleand permitting the contact shoes of the plug to engage receptaclecontacts 16-18. The plug may then be rotated until the contact shoeshave moved under the overhanging segments 31-34 of the top wall of thereceptacle housing 30 between the grooves 35-38. The plug and receptacleparts of the connector will then remain connected together until reverserotation occurs.

Cruciform ribs are formed in the face of the closure member 40 whichengage in complementary cruciform grooves in the end portion 56e of thepost 56. This engagement prevents inadvertent reverse rotation andpopping out by the plug part after it has been connected with thereceptacle part.

The foregoing describes a connector structure which has heretofore beenused commercially. But heretofore the dimensions, thicknesses andspacings of the configurations of the parts resulted in too great travelof the closure inwardly before the plug contact shoes engaged thereceptacle contacts; and, conversely, when the plug contacts separatedfrom the receptacle contacts, if current was flowing, arcing wouldresult which persisted too long and caused excessive burning of thecontacts and shortened contact life. In some cases, the arc would evenjump to the metal protective shell, which was grounded, causing a shortcircuit. In other words, while the closure, when closed, covered thecontacts and protected workers from touching the contacts, it did notsatisfactorily perform as an arc quenching or extinguishing means.

To overcome this defect in the prior art, I have provided an annularrecess or depression 42 in the outer face of the closure member 40 andhave reduced the diameter of the end portion 56e of the plug post 56 sothat it may enter the depression. This depression 42 creates an annularrim 44 on the closure so that the overall thickness of the closure neednot be affected. Moreover, the upper or outer surface of this rim 44 isbrought closer to the plug contact shoes than was their proximity to thesurface of the closure heretofore.

In practice, as shown in the partly inserted position of the plug inFIG. 2, the rim 44 of the closure moves down and passes the level orplane of the tips of the receptacle contacts such as 16 and 18 with lesstravel and sooner than heretofore. Also, reversely, on withdrawal of theplug, the closure reaches the closing level (i.e. when the closure rim44 reaches the plane of the underside of the overhanging segments 3134)sooner than heretofore because it does not have to travel so far. Fromthe foregoing, it is obvious that when the closure rim is at saidclosing level, .a barrier of solid insulation (consisting of the closurerim 44 and closure 40 and the housing part 30 of the receptacle) existsbetween the receptacle contacts 16, 17 and 18 and the plug contacts 68,66 and 67. The result is that connectors which heretofore failedUnderwriters overload interruption tests pass such test when myinvention is embodied in them.

The closure acts effectively as an arc quenching and extinguishing meansduring closing as well as shielding the contacts and protecting workersagainst coming in contact therewith in the closed position of FIG. 1.

In S-Wire usage wherein one wire is for grounding the shell of the plugand receptacle parts of the connector, it is desirable to provide asmaller wire terminal. This should firmly grip a grounding wire and alsoengage a contact for flexibly and slidably engaging the shell. Thismakes it possible, after the wires are connected to the terminals, forthe insulating body of the plug or of the receptacle to be slid quicklyand easily into the protective metallic shell without hindrance or needfor preliminary manipulation or adjustment.

As shown in FIG. 4, the terminal and contact structure has three parts.The basic terminal part is stamped from sheet metal as a rectangularstrip which is then bent right a'ngularly midway along its lengthforming two arms 71, 72 with narrowed tail 74 extending beyond theupstanding arm 72. One face of the tail, which may be considered theinner face, is serrated to afford a gripping surface to bite into andfrictionally hold a conductor wire, as will more fully appear. The tail74 receives a hollow rectangularly shaped box-like metallic clampingmember 76 which is open at opposite ends and has a binding screw 77 in atapped hole in the side thereof opposite the striated face 73 of thetail 74 when the clamp is impaled on the tail.

The terminal as thus far described is received in a recess in the postof the receptacle and is secured therein by a rivet or other commonsecuring means.

To electrically connect the terminal to the protective shell, a flexiblecontact stamped from thin sheet metal into substantially right angularshape has one of its legs 79 laid on the inner surface of the terminalarm 71 and secured thereto by the aforementioned rivet or other commonsecuring means. The other leg 78 of the contact is bent slightlyoutwardly from the periphery of the receptacle base 12. A shallow recessis molded in said periphery so that when the receptacle is slid into itsshell, the leg 78 may bend inwardly into the recess as the leg engagesslidably with the shell and makes electrical connection therewith. Thus,the shell may have a close fit with the receptacle due to the leg movinginto the recess and slidably engaging the shell.

The same terminal and ground contact construction is used on the plug toground its shell.

Modifications within the scope of the invention will occur to thoseskilled in the art. Therefore, the invention is not limited to thespecific form illustrated and described.

What is claimed is:

1. An electrical connector comprising a receptacle having an insulatingbody with a central cavity extending into said body from one face andlongitudinally extend ing channels in the walls of said cavity,receptacle contacts in said channels, a slidable closure of insulatingmaterial in said cavity having radial extensions entering said channels,means biasing said closure outwardly in position to close the entranceto said cavity, a recess in the outer face of said closure providing aperipheral rim around said outer face, the outer surface of said rimbeing coplanar with said one face of said insulating body, incombination with a plug member of insulating material having a centralpost configured to enter said central cavity when pressed against saidclosure, plug contacts on the periphery of said post position to slidewithin said channels as said post is inserted in said cavity, means onsaid plug member and said receptacle body interlocking upon relativetwisting of said member and body to hold the tWo together, the end ofsaid post being reduced in size and configured to fit within said recessin said closure and to be turnable therein, said recess and said reducedend lessening the distance that the plug contacts must move to engagethe receptacle contacts after the plug engages the closure, and alsolessening the distance that said rim must travel to provide a solidinsulation barrier, as compared with the same distances of travel whenthe plug end is not reduced and there is no recess for it in saidclosure for a reduced plug end, said closure and insulating bodycooperating to provide said barrier and to quench arcing between theplug and receptacle contacts as they separate.

2. A ground wire terminal and contact construction in combination withan insulating connector body and a metallic protective shell around saidbody, said terminal and contact construction comprising a stamped sheetmetal member having two arm portions at a right angle to each other, afinger extending from one of said portions, a hollow tubular clampingmember embracing said finger, means on said clamping member to clamp awire against the surface of said finger, said hollow clamping member andsaid stamped member being received in a recess in said insulating body,a flexible contact member having two legs bent at approximately rightangles to each other, and means to secure one leg thereof against thesecond of said arm portions upon the insulating body with the other ofsaid legs in position to resiliently engage said shell. 9

References Cited UNITED STATES PATENTS 2,986,612 5/1961 Healy ZOO-51.093,131,012 4/1964 Healy 33914 3,168,624 2/1965 Healy 339-5109 3,173,7393/1965 Carlson 339-272 ROBERT K. SCHAEFER, Primary Examiner.

ROBERT S. MACON, Examiner. D. SMITH, Assistant Examiner.

1. AN ELECTRICAL CONNECTOR COMPRISING A RECEPTACLE HAVING AN INSULATINGBODY WITH A CENTRAL CAVITY EXTENDING INTO SAID BODY FROM ONE FACE ANDLONGITUDINALLY EXTENDING CHANNELS IN THE WALLS OF SAID CAVITY,RECEPTACLE CONTACTS IN SAID CHANNELS, A SLIDABLE CLOSURE OF INSULATINGMATERIAL IN SAID CAVITY HAVING RADIAL EXTENSIONS ENTERING SAID CHANNELS,MEANS BIASING SAID CLOSURE OUTWARDLY IN POSITION TO CLOSE THE ENTRANCETO SAID CAVITY, A RECESS IN THE OUTER FACE OF SAID CLOSURE PROVIDING APERIPHERAL RIM AROUND SAID OUTER FACE, THE OUTER SURFACE OF SAID RIMBEING COPLANAR WITH SAID ONE FACE OF SAID INSULATING BODY, INCOMBINATION WITH A PLUG MEMBER OF INSULATING MATERIAL HAVING A CENTRALPOST CONFIGURED TO ENTER SAID CENTRAL CAVITY WHEN PRESSED AGAINST SAIDCLOSURE, PLUG CONTACTS ON THE PERIPHERY OF SAID POST POSITION TO SLIDEWITHIN SAID CHANNELS AS SAID POST IS INSERTED IN SAID CAVITY, MEANS ONSAID PLUG MEMBER AND SAID RECEPTACLE BODY INTERLOCKING UPON RELATIVETWISTING OF SAID MEMBER AND BODY TO HOLD THE TWO TOGETHER, THE END OFSAID POST BEING REDUCED IN SIZE AND CONFIGURED TO FIT WITHIN SAID RECESSIN SAID CLOSURE AND TO BE TURNTABLE THEREIN, SAID RECESS AND SAIDREDUCED END LESSENING THE DISTANCE THAT THE PLUG CONTACTS MUST MOVE TOENGAGE THE RECEPTACLE CONTACTS AFTER THE PLUG ENGAGES THE CLOSURE, ANDALSO LESSENING THE DISTANCE THAT SAID RIM MUST TRAVEL TO PROVIDE A SOLIDINSULATION BARRIER, AS COMPARED WITH THE SAME DISTANCES OF TRAVEL WHENTHE PLUG END IS NOT REDUCED AND THERE IS NO RECESS FOR IT IN SAIDCLOSURE FOR A REDUCED PLUG END, SAID CLOSURE AND INSULATING BODYCOOPERATING TO PROVIDE SAID BARRIER AND TO QUENCH ARCING BETWEEN THEPLUG AND RECEPTACLE CONTACTS AS THEY SEPARATE.